Some motor vehicles are built on a full frame that includes left and right frame rails connected by cross members so as to form a ladder-like frame structure. In this type of construction, the frame and the vehicle body are constructed seperately, and each is a complete unit by itself. The left and right frame rails run the length of the vehicle between the front bumper and the back bumper. The front and rear axles are mounted on the frame. The engine and transmission are mounted on the frame. The vehicle body is married to the frame and includes a bulkhead that separates the occupant compartment from the engine compartment. The fenders are then mounted on the frame and the bulkhead to surround the engine.
Other motor vehicles have the frame and the body integrated together into a single one-piece structure that is comprised of a large number of parts that are welded together so that the front fenders, radiator support, and bulkhead are joined together as a unit. In this way, the one-piece body and frame unit defines both the engine compartment and the passenger compartment. This type of body construction is commonly referred to as a unibody construction, or an integral frame and body construction. In this unibody construction, the engine is mounted on an engine cradle, and then the engine cradle is bolted to the underside of the unibody construction. In the unibody construction, the entire single piece structure performs as a load-carrying member that reacts to all loads experienced by the vehicle, including road loads, cargo loads and impact loads. It would be desirable to provide alternative vehicle constructions that would provide new and different management of impact loads in which loads that would otherwise be transferred into the unibody are, instead, transferred into the cradle.